Morphological brain asymmetries in male mice withcallosal defects due to prenatal gamma irradiation

Abstract

We have previously suggested a relationship between the development of the corpuscallosum and the direction of cerebral asymmetries (Schmidt and Caparelli-Dáquer, 1989 ; Schmidt et al., 1991). Here we report a study on morphological brainasymmetries using a distinct experimental approach. At embryonic day 16, mice were exposed toa gamma source, receiving a total dose of 2 Gy. At adulthood 32 irradiated and 28 normal maleSwiss mice were evaluated for individual and populational interhemispheric asymmetries ofweight, dorsal area, and neocortical volume. All irradiated mice showed callosal defects rangingfrom total absence to a partial reduction of the midsagittal callosal area. The normal and irradiatedgroups displayed a pronounced individual asymmetry in all measurements. In contrast,populational asymmetry could be identified only in the normal group. These results are consistentwith our previous data in acallosal mutant mice and support the hypothesis that the corpuscallosum may play a role in directing interhemispheric morphological brain asymmetries.